This invention relates generally to systems for storing, conveying and metering at least one substance used in producing a blend of material, and more particularly, but not by way of limitation, to an ocean-going integrated system for producing a fracturing fluid blend and for pumping the blend into an offshore well.
In the oil and gas industry, it is well known that in creating an oil or gas well various fluids or flowable blends need to be prepared for pumping downhole to accomplish different, known purposes. In hydraulically fracturing a selected formation within a well, a fracturing fluid, comprising a selectable combination of substances or materials, needs to be produced and pumped downhole. For example, a liquid gel concentrate might be mixed with selectable ones of several known additives to produce a mixture which is then blended with sand or other particulate material, preferred to as a proppant, to produce the fracturing blend which is to be pumped downhole. Such a blend is prepared at the well site, which requires storage facilities for storing the substances to be mixed and blended, equipment for mixing and blending the substances, and equipment for pumping the resultant blend into the well.
The need for such fluids and the equipment for producing and pumping such fluids has been recognized and has, to some degree, been met by individual pieces of equipment which are separately transported to a common site for use collectively in producing and pumping the blend. Mixing and blending equipment are described in U.S. patent application Ser. No. 483,001, Apparatus and Method for Mixing a Plurality of Substances, filed Apr. 6, 1983, now U.S. Pat. No. 4,538,221, and in U.S. patent application Ser. No. 483,031, Apparatus and Method for Mixing a Plurality of Substances, filed Apr. 6, 1983, now U.S. Pat. No. 4,538,222. A proppant conveying system is described in U.S. patent application Ser. No. 894,440, filed July 31, 1986, a continuation of U.S. patent application Ser. No. 687,094, Transportable Material Conveying Apparatus, filed Dec. 28, 1984, now abandoned. These patents and this application, which have been assigned to the assignee of the present invention, disclose equipment which has been in public use for more than one year. These patents and this application are incorporated herein by reference both for the background and prior art disclosures made therein of pertinence to the present invention and for the disclosure of equipment exemplifying the type of individual elements which can be adapted for use in the present invention.
One shortcoming of the aforementioned prior art is that many separate pieces of equipment must be separately transported and assembled together for each fracturing, or other type of fluid preparation and pumping, job. This requires maintaining logs of the individual pieces of equipment to insure that suitable ones will be available when needed. This also requires repeated assembly and disassembly of the separate elements from job to job. Therefore, there is the need for an integrated system in which all necessary materials or substances can be stored, mixed, blended and pumped without the need to individually collect, assemble and disassemble separate pieces of equipment for each fluid producing and pumping job. This need contemplates that the original construction of the overall system is to include the use of a single transportation vehicle so that all of the equipment of the system can be fixed to the vehicle and simultaneously transported thereby.
The foregoing need has become particularly critical for offshore drilling operations where it may be even more inefficient to try to assemble on the offshore drilling platform, or to provide from a number of floating vessels, the type of storage, conveying and metering system necessary to properly produce and pump a blend into an offshore well. Therefore, there is the more particular need for an ocean-going integrated system which can be readily moved from one offshore well to another to provide the entire means necessary to produce a selectable type of blend.